1. Technical Field
The present invention relates to electronic thermostats for heating/cooling systems and, more particularly, to thermostats employing a user-interactive microprocessor controlled by unique software to facilitate installation and user interaction.
2. Discussion of the Prior Art
The specific embodiment of the present invention described herein is disclosed in the context of the heating/cooling system that is the subject of our U.S. Pat. No. 4,725,001, issued Feb. 16, 1988, the disclosure of which is expressly incorporated herein in its entirety by this reference. In fact, a portion of the present invention was initially disclosed in that patent. It is to be understood, however, that the inventive concepts utilized in the specific disclosed embodiment of the present invention have application in a wide variety of types of heating, ventilating and air-conditioning (HVAC) systems and are not limited to the particular system disclosed in the aforementioned patent.
There are numerous electronic thermostats known in the prior art, some of which are disclosed in U.S. Pat. Nos. 4,172,555 (Levine '555); 4,199,023 (Phillips); 4,206,872 (Levine '872); 4,356,962 (Levine '962); 4,408,711 (Levine '711); 4,460,123 (Beverly); 4,469,274 (Levine '274); and 4,473,183 (Kensinger et al.). Some of these electronic thermostats include microprocessors controlled by specifically formulated software designed to effect intended heating/cooling system operation. Specifically, the aforementioned Beverly patent discloses a thermostat utilizing a microprocessor. All prior art electronic thermostats have been difficult for the average homeowner to install, particularly when replacing a thermostat in a pre-existing HVAC system. In particular, the wires of an existing system are not labeled as to function, (i.e., burner, fan, air conditioner, voltage supply, etc.) and it is quite likely that the wires can be improperly connected, possibly causing damage system equipment. Consequently, the installation of prior art electronic thermostats, has required trained personnel to avoid damage to the system.
In addition, when a thermostat is replaced in a pre-existing HVAC system, it is possible that the new thermostat will be incompatible with the pre-existing system. For example, in the case of the HVAC system described in our aforementioned U.S. Pat. No. 4,725,001, the system utilizes a unique cycling arrangement of on-time and pause intervals. That particular cycling arrangement may not be compatible with heat pumps or with certain types of boiler heating units, namely: (1) steam radiator heating systems; or (2) any boiler in which the fluid is heated by an immersion type heater such that the fluid temperature and fluid circulation are separately controlled. Under such circumstances the homeowner/operator must be made aware of the incompatibility and must be instructed to either have the system modified or to return the thermostat to the place of purchase.